Over temperature protection method and device for a central processing unit

ABSTRACT

An over temperature protection method and its circuital device for a central processing unit includes a read and write memory unit having pre-stored therein; an instruction for identifying a type of CPU and automatically predetermining the maximum allowable over temperature for the CPU. An over temperature is detected by a heat sensitive resistance installed at the space immediately under the CPU to cause an audio frequency alarm circuit to output a sound alarm and also cause the CPU to slow down its operation speed to an appropriate reduced rate to prevent CPU from being damaged by over heat or other loss caused by interrupting CPU operation. After recovery of temperature to a normal value, the CPU can be instructed to operate with its normal speed.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an over temperature protection methodand its circuital device for a central processing unit, and moreparticularly, an over temperature protection method and its relatedcircuital device for a central processing unit (hereinafter, beabbreviated as to CPU) compatible with a conventional ventilating fanfor dually protecting a CPU from being damaged due to temperature.

2. Description of the Prior Art

In the past, the operation speed of a computer CPU was so slow that itdid not have a problem of over heating. But the operation speed hasincreased several times in this decade with rapid progress of computersoftware industry. Nowadays the operation speed of an average sized CPUhas become so rapid that installation of heat dissipation fins orventilation fans is no longer sufficient. As the temperature of a CPUbecomes too high, not only the life of the computer will be affected,but the computer may even break down which is catastrophic in the fieldssuch as national defense security, nuclear engineering or medicalapplication etc. It is not the time for us to overlook the seriousnessof CPU overheating, and moreover, now it is imperative that we should dosomething to solve this problem.

SUMMARY OF THE INVENTION

In view of the above described situation, it is a main object of thepresent invention to provide an over temperature protection method andits circuital device for a CPU which is able to automatically anddirectly instruct a CPU to decrease the rate of heat generation, and amethod to reduce the basic ambient temperature to assure the security ofthe CPU, and maintain the operation information necessary for continuousinstruction to the CPU for reducing heat generation.

It is another object of the present invention to provide an overtemperature protection method and its circuital device for a CPU whichis able to identify the type of CPU during operation and further,automatically select a predetermined detecting value for protection.

It is a further object of the present invention to provide an overtemperature protection method and its circuital device which is able towarn the user by reducing heat generation by slowing down operationspeed of CPU and informing the user of the situation that it is overheated, or that a conventional ventilation installation has failed, andat the same time, to warn the user with sound for double alarming.

The above mentioned objects of providing an over temperature protectionmethod and its circuital device has been successfully realized through along term study and experiment by the inventor.

The main advantage of the method and device of present invention is thatit can effectively assure the security of CPU to operate normallywithout sudden failure caused by over temperature, and moreover, it iscompatible with a conventional ventilation fan for dually protecting aCPU from being damaged by over temperature.

Another advantage of the method and device according to the presentinvention is that there are several ways of warning of over temperaturestates such as, decreasing operation speed, and displaying or alarmingusing sounds, which can selected by a user to effectively protect hisCPU from being over heated.

A more complete understanding of these and other features and advantagesof the present invention will become apparent from a carefulconsideration of the following detailed description of certainembodiments illustrated in the accompany drawings:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a drawing showing a flow chart of the over temperatureprotection method for a CPU of the present invention;

FIG. 2 is a table enumerating recommended working temperatures of chipsemployed in different types of CPU.

FIG. 3 is a drawing of circuital layout of over temperature protectionfor a CPU in a preferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIG. 1, showing a flow chart of the over temperatureprotection method for a CPU of the present invention, an on/offinstruction and an instruction for identifying the type of CPU arepre-stored in a read and write memory unit (BIOS) so that when operationof the computer is initiated 20, CPU 30 will directly read the abovementioned instruction from the BIOS memory unit 10 and instruct a chipcircuit (PII×4 type chips) 40 to operate, and at the same time energizeon/off function circuit 50. Circuit 50 is the main switch circuit forautomatic control, and unless it is instructed to be in ON state, thedevice of the present invention does not function. Then the CPU 30identifies its own type to select a mode for a temperature detectingmode select circuit 60 and match it with a temperature sensing heatsensitive resistance 70 installed adjacently right under said CPU 30.

As the working temperature of CPU 30 rises, the value of temperaturesensing heat sensitive resistance 70 decreases linearly, and thepotential of a resistor connected to its one terminal will inverseproportionally increase to a starting value as soon as the workingtemperature of CPU 30 reaches a predetermined value. Then an overtemperature actuating circuit 80 is actuated and outputs a signal (LO)to an over temperature alarm circuit 90 for energizing it. At this timesince both the pre-located functional ON/OFF circuit 50 and the overtemperature alarm circuit 90 are cascadely grounded, an audio frequencyalarm circuit 100 is energized and outputs a sound alarm, and the signal(LO) is sent to a chip circuit 40 via another circuit for the chipcircuit 40 to output a (REFRESH) signal to a frequency eliminatingcircuit 110 to initiate it. At this time the output from the frequencyeliminating circuit 110 is input to a frequency eliminating controlcircuit 120 to split the (SYSCLK) signal which is coming from the frontof chip circuit 40, and control the (STPCLK) terminal 31 of CPU 30 withsaid split (SYSCLK) signal to slow down the operation speed of CPU 30.The heat generated from CPU 30 is therefore reduced to the extent whichis able to assure CPU 30 to work continuously and keep effectively theinformation on line.

After the over temperature hazard is released, the over temperatureswitch circuit 80 returns to its de-energized state and other circuitsalso recover their normal states without any output.

Accordingly, CPU 30 recovers its operation with normal speed. Of coursethe user may take appropriate responses such as inspecting the innerpart of the computer or replacing the heat dissipating equipment etc.without haste during the dual emergency state of slowing down of CPU 30in response to sound alarm, or afterwards asks for an experiencedengineer to make a thorough inspection.

Referring to the table of FIG. 2, which is a table enumeratingrecommended maximum working temperatures of chips employed in differenttypes of CPU, wherein the recommended temperatures are 65° C. for INTELand AND/K5, 70° C. for CYRIX and IBM, 75° C. for AND/K6, 80° C. for Xrespectively. The above recommendation is made based on the variation ofoutput value between 0 and 1 of the output terminals (e.g. #GP00 andGP08) of the chip circuit 40, and is also the basis of deciding whetherthe resistances R61, R62 and R63 are to be connected in parallel, or inany other forms, and to allot the ratio of working voltage between theheat sensitive resistance 70 and the resistances R61, R62, and R63 inorder to determine the detecting temperature. In the illustratedembodiment, the values of over temperature for GP00 and GP08 aredetermined as 65° C. at(0,0), 70° C. at (1,0), 75° C. at (0,1) and 80°C. at (1,1). By means of decreasing the heat sensitive resistance 70 andconnecting a resistance in series to the other terminal, the object ofincreasing a predetermined value of over temperature is attained.Decreasing the predetermined value of over temperature may be carriedout in a reversed way.

Referring to FIG. 3, which is a circuital layout of over temperatureprotection for a CPU in the preferred embodiment of the presentinvention, the circuit of the present invention comprises a read andwrite memory unit (BIOS) 10, a CPU 30 for matching the computer, a chipcircuit (PII×4 type chips) 40, a functional on/off circuit 50 composedof transistors Q₁, Q₂, a temperature detecting mode selection circuit 60principally formed of transistors Q₃, Q₄ and selection resistances R62,R63, R61 connected in parallel, a temperature sensing heat sensitiveresistance 70 connected in series to said temperature detecting modeselection circuit 60, an over temperature actuating circuit 80principally formed of a transistor Q₅, an over temperature alarm circuit90 principally formed of transistors Q₆, Q₇, an audio frequency alarmcircuit 100 composed of oscillators 101, 102, transistors Q₈, Q₉ andspeaker 103, a 1/16 frequency eliminating circuit 110, and a frequencyeliminator control circuit 120 principally composed of a flip-flop 121and a transistor Q₁₀, wherein the functional on/off circuit 50 may bereplaced by a switch means to be manually operated, and switching of theresistance R62, R63 may be carried out by manual switches and theirratio can also be adjusted by employing the resistances having positivetemperature coefficient in coordination with the heat sensitiveresistance 70. The frequency eliminating circuit 110 may be enlarged andinclude more components to select other values of frequency forelimitating. The chip circuit 40 also may be enlarged to increase itsfunctions so as to control a conventional ventilation fan.

Referring now to FIGS. 1, 2 and 3, the operational principle of thecircuital device of the present invention is described as follows: Uponinitiating computer 20, CPU 30 identifies read and write memory unit 10and instructs 41 terminal of the chip circuit 40 to output a (LO) signalto turn off transistor Q₁ and turn on transistor Q₂, and a signal isoutput from terminal 46 (PCIRST-) to clear flip flop circuit 121. As thetemperature sensing heat sensitive resistance 70 is heated to reduce itsresistance to a predetermined value, the potential at point A rises toturn on transistor Q₅, at which moment point B becomes the (LO) state(LO), at which transistor Q₆ turns off, and transistor Q₇ turns on,causing point C to then be at a grounded state. Thus, being driven byoscillators 101, 102, transistors Q₈, Q₉ oscillate and drive the speaker103 to produce an alarming sound, and at the same time, the (LO) stateat point B is transmitted to terminal 44 (GPI8) of chip circuit 40 viaanother circuit. Then at the terminal 45 (REFRESH) of chip circuit 40, asignal for frequency eliminator circuit 110 is output to produce a 1/16eliminated frequency output, which reacts with the clock output fromterminal 46 (SYSCLK) of the chip circuit 40 in the flip flop 121 anddrives transistor Q₁₀ to repeat on/off operation with the rate of 1/16(SYSCLK) clock.

Next, the signal is input to the terminal (STPCLK-) of CPU 30 connectedto the collecter of Q₁₀ and slows down the running speed of CPU 30 to1/16 that of its original one, and also reduces heat generation rate. Insuch way, the accumulated heat is dissipated gradually and the danger ofCPU 30 being damaged by over temperature is released thereby. After thetemperature of CPU 30 goes down, the resistance of heat sensitiveresistance rises up to a certain value, the potential of point Adecreases correspondingly so that transistor Q₅ returns to its normallyturn off state, and at this moment the potential of point B also isrecovered to its normal state (HI), and transistor Q₆ turns on againwhile transistor Q₇ turns off, while point C recovers its open circuitstate, the audio frequency alarm circuit 100 stops outputting and theinput signal of terminal 44 (GP18) of chip circuit 40 also recovers to a(HI) state. Accordingly, terminal 45 of chip circuit 40 stops outputtingthe (REFRESH) signal, the flip flop 121 stops outputting and transistorQ₁₀ turns off, at which terminal (STPCLK-) of CPU 30 recovers its normalstate and CPU 30 recovers its normal operation speed too.

It is clear from the above description that, the advantage of the methodand device according to the present invention is that, it caneffectively assure security of the CPU to operate normally withoutfailure caused by over temperature and moreover it is compatible with aconventional ventilation fan for dually protecting a CPU from beingdamaged due to over temperature.

Although the present invention has been described with a certain degreeof particularity, the present disclosure has been made by way of exampleand changes in details of structure may be made without departing fromthe spirit thereof.

What is claimed is:
 1. An over temperature protection method for acentral processing unit (CPU), comprising the steps of:first,pre-storing an on/off instruction and an instruction for identifying atype of CPU in a read and write memory unit of a basic input/outputsystem (BIOS) circuit when the CPU is initialized, and causing the CPUto directly read the instruction from said BIOS memory unit and instructa chip circuit to operate, and at the same time energizing a main switchof an on/off function circuit, second, selecting a mode for atemperature detecting mode select circuit based on identification bysaid CPU of its own type, and matching the selected mode with atemperature sensing heat sensitive resistance installed adjacently undersaid CPU so that as a working temperature of the CPU rises, the value oftemperature heat sensitive resistance linearly varies, and the potentialof a resistor connected to one terminal of the temperature heatsensitive resistance also varies inverse proportionally to a startingvalue, until the working temperature of the CPU has reached apredetermined value, third, actuating an over temperature circuit tooutput a signal to an over temperature alarm circuit for energizing theover temperature alarm circuit, at which time, since both the on/offcircuit and the over temperature alarm circuit are mutually cascadelygrounded, an audio frequency alarm circuit controlled by the functionalon/off circuit is energized, fourth, outputting an audible alarm fromsaid audio frequency alarm circuit and sending said signal to the chipcircuit via another circuit, fifth, outputting a signal from said chipcircuit to a frequency eliminating circuit to initiate the frequencyeliminating circuit, sixth, inputting the output from said frequencyeliminator circuit to a frequency eliminating control circuit to split asystem clock signal output by said chip circuit to slow down anoperation speed of the CPU, and, finally, after the heat generation bythe CPU is reduced due to said slow down to a value which is able toensure that the CPU will work continuously without interrupting flow ofinformation being processed, and an over temperature hazard is released,returning the over temperature circuit to a de-energized state andrestoring other circuits to their normal state without any output. 2.The method as claimed in claim 1, wherein said temperature detectingheat sensitive resistance is installed in a space adjacently right undersaid CPU.
 3. An over temperature protection circuit device for a centralprocessing unit (CPU), comprising:a read and write memory unit of abasic input/output system (BIOS) circuit matched with the CPU of thecomputer; a chip circuit; a functional on/off circuit; a temperaturedetecting mode selection circuit principally formed of transistors Q₃,Q₄ and at least one selection resistance connected in parallel; an overtemperature actuating circuit; an over temperature alarm circuit: anaudio frequency alarm circuit composed of oscillators, transistors and aspeaker; a frequency eliminating circuit; and, a frequency eliminatingcontrol circuit, wherein said frequency eliminator circuit is enlargedand includes additional components to select other values of frequenciesto be eliminated.
 4. An over temperature protection circuit device asclaimed in claim 3,wherein the resistance employed in said temperaturedetecting mode selection circuit is a resistance having a positivetemperature coefficient of resistance for cooperatively operating withsaid heat sensitive resistance.